Circuit configuration for starting and operating at least one discharge lamp

Abstract

A circuit arrangement for starting and operating at least one discharge lamp is provided.

Description

TECHNICAL FIELD[0001]The present invention relates to a circuit arrangement for starting and operating at least one discharge lamp with a first input terminal and a second input terminal for connecting a supply voltage, an inverter, which includes at least one first main transistor and one second main transistor in a half-bridge arrangement, which main transistors are coupled in series between the first input terminal and the second input terminal, a first output terminal and a second output terminal for connecting the at least one discharge lamp, at least one lamp inductor, which is coupled in series with the first output terminal, at least one capacitor, which is coupled in parallel with the first output terminal and the second output terminal, a transformer with a primary winding and a first secondary winding and a second secondary winding, a series circuit including the primary winding and the at least one lamp inductor being coupled between the half-bridge center point and a re...

AI Technical Summary

Benefits of technology

[0005]The present invention is therefore based on the object of developing the circuit arrangement mentioned at the outset in such a way that a reduction in the control losses is made possible without the risk of destruction of the main transistors of the inverter and / or without the need to increase the dimensions of the main transistors of the inverter.

[0008]As a result of the configuration according to the invention, it is possible using a few very inexpensive standard component parts to ensure good reproducibility of the open-circuit voltage and the operational parameters, i.e. the parameters for the continuous operation of the discharge lamp, with at the same time markedly reduced control losses. In an exemplary embodiment which has been implemented, the control losses could be reduced by approximately 80%.

[0010]In a preferred embodiment, the at least one second auxiliary transistor has a control electrode, a working electrode and a reference electrode, the working electrode being coupled to that point of the associated voltage divider at which the inductance is coupled to the nonreactive resistor, the reference electrode being coupled to the associated second secondary winding. This circuitry ensures, in a simple manner, that the inductance of the frequency-dependent voltage divider can be bridged by virtue of the second auxiliary transistor if the second auxiliary transistor is switched into the on state.

[0012]Preferably, it is furthermore provided that a further nonreactive resistor is coupled between the working electrode of the at least one second auxiliary transistor and that point of the associated voltage divider at which the inductance is coupled to the nonreactive resistor. A nonreactive resistor provided at this point acts as a current-limiting resistor and thus ensures that the current driven by the transformer continues to flow substantially through the current-measuring resistor and thus keeps the second auxiliary transistor safely turned on.

Problems solved by technology

One disadvantage with the solution in accordance with the mentioned document is the considerable control losses, since precise zener diodes with a low dynamic resistance, as are required for this solution, are only available above approximately 7 V, and the voltage generated via a current-measuring resistor during lamp operation is of this order of magnitude.

This also results in a large, undesired spread.

It should be taken into consideration here that operation of the lamp inductor with slight saturation is desirable, however, since this results in low losses.

It is precisely at this point that an increase in the tolerances becomes noticeable as a negative factor since, as a result, the risk of saturation of the lamp inductor arises.

As a result, a reduction in the control losses would in this way result in the component parts of the circuit arrangement being provided with increased dimensions and therefore in increased costs.

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